Air-bag arrangement

ABSTRACT

An air-bag arrangement includes an air-bag and a gas generator to supply gas to inflate the air-bag. The gas generator is hingedly connected to a support and is hingedly movable between a closed position in which the gas generator extends across and closes an aperture, and a second position in which the apertured is opened to permit the flow of gas from the air-bag. The gas generator is initially retained in position by a retainer the retainer being actuable, in response to a signal, to enable the gas generator to move hingedly to the open position.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to PCT/SE03/00750, filed May 5, 2003,and GB0212921.1, filed Jun. 5, 2002.

BACKGROUND OF THE INVENTION

The present invention relates to an air-bag arrangement, and moreparticularly relates to an air-bag arrangement adapted to becontrollably vented.

It is known that it is desirable to vent an air-bag provided for use ina motor vehicle to protect an occupant of the vehicle in the event thatan accident should occur, especially if the air-bag is of the typeintended to provide protection in the event that a front impact shouldoccur.

An air-bag that is intended to provide protection in the case that afront impact should occur is generally located so that, when inflated,the air-bag is positioned in front of the occupant to be protected.During the front impact the vehicle decelerates suddenly. Due toinertia, the occupant of the vehicle tends to continue moving, and thusthe occupant of the vehicle is, in effect, moving forwardly relative tothe rest of the vehicle. The function of the air-bag is to deceleratethe occupant, preferably in such a way that the occupant suffers noinjury. The air-bag must be inflated very swiftly and thus, typicallycontains relatively high-pressure gas. If the air-bag were not vented,then because of the high gas pressure within it, the air-bag would notdecelerate the occupant in a desired manner. Thus many air-bags areprovided with vent holes formed in them so that, when the air-bag isstruck by the occupant, gas can escape from the air-bag through the venthole or holes, so that the air-bag serves the function of deceleratingthe occupant more gently, to avoid such injury.

In many cases it is desirable to be able to control the degree ofventing, or the time at which venting commences. For example, if anoccupant of a seat is out of the ordinary seating position and is, forexample leaning forwardly, then it is desirable to commence venting ofthe air-bag at a very early stage during its inflation. Varying degreesof venting may be desirable depending upon the weight and/or size of theoccupant to be protected by the air-bag.

Various mechanisms have been proposed previously for the controllableventing of an air-bag.

The present invention seeks to provide an improved air-bag arrangement.

SUMMARY OF THE INVENTION

Further to the present invention, there is provided an air-bagarrangement comprising an air-bag, and a gas generator to generate gasto inflate the air-bag, the gas generator being hingedly connected to asupport so as to be moveable between a closed position in which part ofthe gas generator extends across an aperture communicating with theinterior of the air bag to close the aperture, and a second position inwhich the aperture is opened to permit the flow of gas from the air-bag,the gas generator initially being retained in the closed position by aretainer, the retainer being actuable, in response to a signal, toenable the gas generator to move hingedly to the open position

Preferably, the retainer is actuated by a pyrotechnic charge.

Advantageously, the retainer includes at least one catch which initiallyextends over part of a flange carried by the gas generator, the retaineralso including an arrangement to move one or more of the catches to aposition in which it does not extend over the flange of the gasgenerator.

Conveniently, one or more of the catches comprises an elongate elementpivotally mounted at one end adjacent to part of the flange, part of oneor more of the catches overlying the flange and being arranged so thatactuation of a piston-and-cylinder arrangement will cause the catch tomove to a position in which it no longer overlies the flange.

Preferably two catches are provided.

Advantageously, one or more of the catches are provided with asubstantially centrally located pivot, a first part of the catch to oneside of the pivot engaging with the flange, the other part of the catchbeing located adjacent a piston-and-cylinder device, such that movementof the piston will cause rotation of the catch to a position in whichthe first part of the catch no longer engages the flange.

Conveniently, the retainer comprises an exploding bolt.

Preferably, the retainer comprises a piston-and-cylinder unit arrangedto engage and move part of a flange carried by the gas generator so asto move the gas generator to the open position.

Advantageously, the retainer comprises an expandable element whichengages part of a flange carried by the gas generator, the expandableelement on expansion thereof, serving to move the gas generator to theopen position.

Conveniently, the expandable element is plastically deformable.

Preferably, the expandable element comprises a bellows arrangementprovided with a pyrotechnic device.

In order that the invention may be more readily understood, and so thatfurther features thereof may be appreciated, embodiments of theinvention will be described, by way of example, with reference to theaccompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly sectional and partly elevational view of a part of anarrangement in accordance with the invention, illustrating the gasgenerator and part of the air-bag,

FIG. 2 is a plan view of the arrangement shown in FIG. 1, illustratingcomponents in an initial position in solid line, and in a final positionin phantom,

FIG. 3 is a view corresponding generally to FIG. 2 illustrating analternative embodiment of the invention in an initial condition,

FIG. 4 is a view corresponding to FIG. 3 showing the embodiment of FIG.3 in an alternate condition,

FIG. 5 is a view corresponding generally to FIG. 2 illustrating afurther embodiment of the invention,

FIG. 6 is a sectional view of part of the embodiment of FIG. 5,

FIG. 7 is a view corresponding generally to FIG. 1 illustrating anotherembodiment of the invention in an initial condition,

FIG. 8 is a view corresponding generally to FIG. 7 showing part of theembodiment of FIG. 7 in an alternate condition,

FIG. 9 is a view corresponding generally to FIG. 1 showing a stillfurther embodiment of the invention,

FIG. 10 is a view corresponding generally to FIG. 9 showing part of theembodiment of FIG. 9 in an alternate condition,

FIG. 11 is a view corresponding generally to FIG. 1, showing anotherembodiment of the invention, and

FIG. 12 is a view corresponding generally to FIG. 11 showing a part ofthe embodiment of FIG. 11 is in an alternate condition.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIGS. 1 and 2 of the accompanying drawings, anair-bag arrangement in accordance with the present invention comprisesan air-bag 1 which may be of any convenient design and which may, inparticular, be an air-bag intended for use in protecting an occupant ofthe vehicle in the case that a frontal impact should arise. Thus theair-bag 1 may be a driver air-bag or passenger air-bag in a motor car.

The air-bag 1 defines an opening or aperture 2 communicating with theinterior of the air-bag 1, and is, in the region of the opening oraperture 2, secured by securing element 3 to a support plate 4. Thesupport plate 4 defines an aperture 5 which is aligned with the aperture2 of the air-bag.

Mounted on the exterior of the support plate 4 is a gas generator 6. Thegas generator 6 is provided with a generally cylindrical housing 7 whichhas a plurality of gas outlet apertures 8. The housing 7 of the gasgenerator 6 is dimensioned to pass through the aperture 5 in the supportplate and through the aligned aperture 2 in the air-bag so that the gasoutlet apertures 8 are located within the interior of the air-bag 1.

The gas generator 6 is provided with a radially outwardly extendingflange 9. In this embodiment of the invention the flange 9 is shown asbeing of square form, but the flange 9 may have any appropriateconfiguration. As shown in FIG. 1, one side edge of the flange 9 isconnected, by means of a hinge 10 to the underside of the support plate4. The entire gas generator 6 is thus connected to the support plate 4in a hinged manner, and can move hingedly, in the manner of a door, froma closed position in which the gas generator 6 extends across theapertures 5,2, to an open position in which the gas generator 6effectively opens the aligned apertures 5, 2 in the support plate 4 andthe air-bag 1 to permit the outflow of gas from the interior of theair-bag 1.

The gas generator 6 is provided with a retainer 11 (illustrated onlyschematically in FIG. 1) which retains the gas generator within itsinitial closed position, as shown in FIG. 1, in which it effectivelycloses the aligned apertures 5,2 in the support plate 4 and the air-bag1.

As can be seen more clearly in FIG. 2, the retainer 11 comprises ahousing 12 defining an axial bore 13, the bore containing two pistons14, 15 which are initially slightly spaced-apart from one another withinthe bore 13. A secondary gas generator 16 is arranged to supply gas tothe region of the bore 13 between the pistons 14, 15.

It is to be understood that when gas is supplied from the secondary gasgenerator 16 upon receipt of a firing signal, the pistons 14 and 15 aredriven outwardly, in opposite directions along the bore 13. The pistons14,15 may, as shown in FIG. 2, be “telescopic” pistons which, onactuation of the secondary gas generator 16, are caused to move to therespective positions illustrated in phantom, in which each pistonextends a substantial distance from the housing 12.

Two pivotally mounted catch elements 17, 18 are provided, of elongateform. The first catch element 17 is mounted pivotally at one end 19thereof to the support plate 4 at a position adjacent the flange 9, fromwhere it extends across part of the flange 9 of the main gas generator6, to a position located adjacent the part of the housing 12 containingthe first piston 14. Similarly the second catch element 18 is mountedpivotally at one end 20 thereof to the support plate 4 adjacent theflange 9 and having the other end thereof located adjacent that part ofthe housing 12 which contains the second piston 15. Again the secondcatch element 18 extends across part of the flange 9 of the main gasgenerator 6. The effect of the catch elements 17, 18 is that the flange9 is retained in position, and thus the main gas generator 6 cannoteffect any hinging movement about the hinge 10, but instead is retainedin its initial closed position illustrated in FIG. 1.

In response to an appropriate firing signal, the secondary gas generator16 may generate gas which flows rapidly and under high pressure into theregion of the bore 13 between the two pistons 14, 15. The pistons 14, 15are thus driven outwardly in opposite directions moving with them theends of the two catch elements 17, 18, thus pivotally moving the catchelements 17,18. The catch elements 17, 18 are moved to the respectivepositions shown in phantom in FIG. 2 in which the catch elements 17, 18no longer extend across any part of the flange 9 of the main gasgenerator 6. The main gas generator 6 therefore becomes free to move toan open position, hinging about the hinges 10, thereby opening thealigned apertures 5, 2 in the support plate 4 and the air-bag 1 to allowgas generated by the main gas generator 6 to flow from the interior ofthe air-bag.

Whilst FIGS. 1 and 2 illustrate one mechanism for retaining the gasgenerator 6 in its initial closed position, alternative mechanisms maybe used. FIGS. 3 and 4 illustrate an alternative arrangement. FIG. 3illustrates the flange 9 of a gas generator 6 of the type describedabove. A rotatable catch element 20 is provided which is mounted forrotation about a substantially centrally located pivot pin 21 connectedto the support plate 4. In an initial position illustrated in FIG. 3, afirst part of the rotatable catch element 20 to one side of the pivotpin 21 is located in overlying engagement with the flange 9 to retainthe gas generator 6 in its initial closed position.

A pyrotechnic unit 22 is provided which has an extending piston 23 whichis arranged so as to engage or bear against a second part of therotatable catch element 20. On actuation of the pyrotechnic unit 22, inresponse to an appropriate signal, the extending piston 23 is movedoutwardly away from the pyrotechnic unit. As shown in FIG. 4, thearrangement is such that this movement of the piston 25 causes the catchelement 20 to rotate about the pin 21 to a position in which the catchelement 20 no longer overlies the flange 9 of the gas generator 6,thereby allowing the gas generator to move about the hinge 10.

FIGS. 5 and 6 illustrate yet another embodiment of the invention inwhich the flange 9 of a gas generator 6 is secured to the support plate4 by means of an explosive bolt. An aperture 30 is formed in the flange9 and an explosive bolt 31 is provided which extends through theaperture 30 in the flange 9 to a corresponding aperture 32 in thesupport plate 4. Contained within the explosive bolt 31 is an explosivecharge 33. On actuation of the explosive charge 33 in response to anappropriate signal, the head 34 of the bolt 31 is blown off to becomedetached from the shank 35 of the bolt 31, and thus the flange 9 of thegas generator 6 is no longer retained in its initial closed position,but instead is free to move about the hinges 10.

Whilst, in the embodiments of FIGS. 1 to 6, the gas generator 6 isinitially retained in position and is then released so as to be allowedto move towards its open position under the influence of gas pressurewithin the air-bag 1, in the following embodiments the gas generator 6is positively driven to an open position.

Referring now to FIG. 7, a retainer and opening mechanism 40 is providedwhich acts initially to retain the gas generator 6 in its initial closedposition, and which is operable to drive the gas generator 6 to an openposition. The retainer and drive mechanism 40 comprises a pyrotechnicunit 41 associated with an extending piston 42. The flange 9 of the gasgenerator is provided with an extension piece 43 which engages with thepiston 42. Initially the retainer and opening mechanism 40 serves tohold the gas generator 6 in the initial closed position, but on firingof the pyrotechnic unit 41 in response to a firing signal, the piston 42extends, as shown in FIG. 8, thus hingedly moving the gas generator 6 toan open position. The degree of extension of the piston 42 may becontrolled in accordance with a control signal, and thus the degree ofventing from the air-bag 1 provided by the described arrangement may becontrolled.

FIGS. 9 and 10 illustrate a further embodiment which is generallysimilar to that of FIGS. 7 and 8. However, instead of using apyrotechnic arrangement with an extending piston, the embodiment shownin FIGS. 9 and 10 utilises an expandable element in the form of anexpandable cylinder 50 as the retainer and opening arrangement. Theexpanding cylinder 50 has an initial predetermined diameter and ismounted in position in such a way that it retains the gas generator 6 inthe desired initial closed position. The expanding cylinder 50 isassociated with a secondary gas generator (not shown) configured tosupply gas to the cylinder 50, the effect of which is to substantiallyincrease the diameter of the cylinder 50. The cylinder 50 may thus bebrought to a condition as shown in FIG. 10 in which the cylinder 50 hasmoved the gas generator 6 to an open condition.

FIGS. 11 and 12 illustrate a still further embodiment of thearrangement. In this arrangement, the flange 9 of the gas generator 6 ishingedly connected to the inside surface of the support plate 4 so thatthe gas generator 6 can move hingedly, in the manner of a door, from theclosed position illustrated in which the gas generator extends acrossthe apertures 5, 2 in an inward manner relative to the air-bag 1 to anopen position. This is in contrast to the above-described embodiments inwhich the gas generator 6 is openable away from the air-bag 1.

The embodiment shown in FIGS. 11 and 12 utilises an expandable bellowsarrangement 60 as the retainer and opening arrangement. The bellowsarrangement 60 comprises an expandable and plastically deformablebladder 61 which has an initial configuration illustrated in FIG. 11 inwhich it is folded or compressed in such a way that it retains the gasgenerator 6 in the desired initial closed position. The expandingbladder 61 is associated with a pyrotechnic device 62 which isconfigured to be energised upon receipt of an appropriate signal so asto inflate, and hence expand the bladder 61. The bladder 61 deformsplastically as it expands from its initial condition illustrated in FIG.11 to its expanded condition illustrated in FIG. 12. As will be clearfrom FIG. 12, as the bladder 61 expands, deforming plastically, itserves to move the gas generator 6 inwardly of the air-bag 1 to an opencondition. Because the bladder 61 deforms plastically as it expands, itresists any tendency for the gas generator 6 to move back towards itsclosed position, for example under the action of the high pressure gaswithin the interior volume of the air-bag 1 upon actuation of the gasgenerator 6.

While the above description constitutes the preferred embodiment of thepresent invention, it will be appreciated that the invention issusceptible to modification, variation and change without departing fromthe proper scope and fair meaning to the accompanying claims.

1. An air-bag arrangement comprising an air-bag, and a gas generator togenerate a gas to inflate the air-bag, the gas generator being connectedto a support so as to be moveable between a closed position in whichpart of the gas generator extends across an aperture communicating withthe interior of the air bag to close the aperture, and an open positionin which the aperture is opened to reduce the pressure of the gas withinthe air-bag, the gas generator initially being retained in the closedposition by a retainer, the retainer being actuable, in response to asignal, to move the gas generator to the open position.
 2. An air-bagarrangement according to claim 1 wherein the retainer is actuated by apyrotechnic charge.
 3. An arrangement according to claim 1 wherein theretainer comprises an expandable element which engages part of a flangecarried by the gas generator, the expandable element, on expansionthereof, serving to move the gas generator to the open position.
 4. Anarrangement according to claim 3, wherein the expandable element isplastically deformable.
 5. An arrangement according to claim 4, whereinthe expandable element comprises a bellows arrangement provided with apyrotechnic device.
 6. An air-bag arrangement according to claim 1wherein the gas generator moves between the open and closed positionthrough movement about a hinge.
 7. An arrangement according to claim 1wherein the gas generator is urged to move to the open position by theretainer.